Here's a quick method for rough conversion from degrees C to degrees F:

Multiply Cº by two.... then add 30 to get approx.  Fº (that's it !)

Examples....

0º C x 2 = 0 plus 30 = 30ºF (actual is 32ºF)

5º C x 2 = 10 plus 30 = 40ºF (actual is 41º)

10º C x 2 = 20 plus 30 = 50º (same as actual)

15ºC....60ºF (59ºF)

20ºC....70ºF (68ºF)

25ºC....80ºF....(77ºF)

30ºC....90ºF (86ºF)

35ºC....100ºF (95ºF)

No good at at temps outside of survival range for humans (and palms) but not a bad rough method for quick conversion

After living in a metric country for 1-1/2 years, I now know whether 12º is a coat, a sweater, or swimming trunks.

As a 'Murkin, my prob's the opposite . . . .

From F to C . . .

Hmm.  100 F, minus 30, equals seventy, divided in half equals 35 C.  

Close enough . . . .

Here is a freeware temp conversion program that works great.

I think the developer is out of business now.

I have been using it for years...

Jeff

www.jeffearl.com/QuickTemp1.exe

I've been using the "mental" conversion for years.  Of course, "being mental" helps.

Here is a freeware temp conversion program that works great.

I think the developer is out of business now.

I have been using it for years...

Jeff

www.jeffearl.com/QuickTemp1.exe

As that link is broken, feel free to bookmark the temp converter on my website.

Celsius and Fahrenheit Conversion

Thanks for the idea, although I would also like to see an eays way from F to C°

Debbie, for °F to °C, just do the same backwards, i.e. subtract 30 then divide by two.

The actual conversion is (-32)/1.8 or, from °C to °F *1.8+32, so it is easy with a calculator or for those who are good at mental arithmatic. For those who have difficulty multiplying or dividng by 1.8 in their head, you can multiply by multiplying by 9 then divide by 5 or to divide, divide by 9 then multiply by 5.

Using easy numbers

10°C =

10 x 1.8 = 18

or 10 x 9 = 90, 90 / 5 = 18.

The 18 + 32 = 50.

Answer 50°F.

Using a more difficult example.

83°F =

83 - 32 = 51

51 / 1.8 = 28.3333

or 51 / 9 = 5.6666, 5.6666 x 5 = 28.3333.

Answer = 28.3°C.

Line three is still fairly difficult for a lot of people to do in their head, but it can be further simplified.

51 / 9 = 5 remainder 6, so the answer will be 5 point something.

Using the remainder of 6.

6 divided by 9 is the same as 60 divdided 9 then divded again by 10.

So 60 / 9 = 6 remainder 6

Divided again by 10 would be 0.6 remainder 0.6.

At this point we already have 5.6, which is accurate enough, but knowing that the remainder is 6 (0.6) again, we know that the actual answer is 5.66 recurring.

5.66 x 5 may be easier to do as 5.66 x 10 then / 2.

5.66 x 10 = 56.6

56.6 / 2 = 28.3

My wife hates maths, so I know that anyone else who feels the same way will probably just see the numbers and instantly switch off, but maths can always be simplified to whatever level you feel comfortable with. I always maintain that anyone who can count to five can do any maths calculation, they just have to know how to make it easy.